KR940007861B1 - Imidized acrylic polymers and process for their preparation - Google Patents

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Description

Imidized Acrylic Polymer and Method for Making the Same

The present invention relates to imidized acrylic polymers and methods for their preparation.

As used herein, the term "acrylic polymer" or "acrylic resin" refers to homopolymers and copolymers of methacrylic acid or alkyl esters of acrylic acid in which the alkyl group contains C ₁ to C ₈ and mixtures thereof.

Examples of methacrylic acid or esters of acrylic acid are methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, secondary-butyl methacrylate, tert-butyl methacrylate, methyl, ethyl, butyl, isopropyl acrylic Rate and the like.

Acrylic polymers or acrylic resins contain units derived from other ethylenically unsaturated monomers such as styrene, α-methyl-styrene, acrylonitrile, acrylamide, or monomers containing double ethylenic unsaturations such as butadiene. can do.

The polymer further has an intrinsic viscosity value as measured in tetrahydrofuran (THF) at 30 ° C., comprised in the range of 0.01 to 7 dl / g, preferably 0.2 to 2 dl / g.

The main drawback exhibited by these polymers is their low glass transition temperature (Tg) which significantly limits their use.

Obtained by reaction of acrylic resin with ammonium hydroxide, ammonium phosphate or alkylamine or partial reaction of the same acrylic resin with ammonium hydroxide and then with alkylamine from United States Patent Nos. 3, 284,425 and British Patent No. 926, 629 It has been known to increase Tg by imidization of polymers.

These methods have several drawbacks: these processes are carried out in an autoclave, are of batch type, require heating and generally have a very long reaction time and require the use of dissolving or suspending solvents.

To overcome this drawback, German Patent No. 1, 077, 872 proposes a process for the production of imidized acrylic polymers in an extruder using ammonium hydroxide in aqueous solution.

However, the product obtained by the method of this patent has a weak thermal stability and must be further treated before use in the conversion step.

US Pat. No. 4, 246, 374 discloses a process for the preparation of imidized acripolymers in an extruder by direct reaction of an acrylic resin with an ammonia or primary amine under substantially anhydrous conditions.

The products thus obtained show excellent thermal stability, but their manufacturing method has an uneconomical disadvantage of requiring a reaction temperature of 450 ° C. and a pressure of 1,000 atmospheres.

The inventors have found that the above mentioned deficiencies can be overcome by preparing imidized acrylic polymers by reaction of acrylic resins with at least one variant having the following general formula (I), which is an object of the present invention:

R-X-NH-R '(I)

Wherein R and R 'are the same or different from each other and are hydrogen, alkyl, cycloalkyl, aryl or alkylaryl groups containing C' to C ₂₀ , and X is -CO-, -COHN-, -NHCO -, -OCO-,-SO _2- , -C ₅ H ₄ SO ₂ -It is a difunctional group selected from the group consisting of.

When R is different from R ', R may contain heteroatoms such as halogen.

Examples of modifiers having formula (I) include acetamide, aniseamide, benzamide, acetanilide, butyramide, benzanilide, propionamide, formamide, N-methyl-acetamide, N-methyl-benzamide , N-methylformamide, N-phenylformamide, benzenesulfamide, ethylcarbamate, benzhydrazide, clopropionamide, N, N'-dimethylurea and the like.

The imidized acrylic polymers obtained by the process of the present invention have an appropriate thermal stability, intrinsic viscosity comprised in the range of 0.01 to 7 dl / g, preferably 0.2 to 2 dl / g in tetrahydrofuran (THF) at 30 ° C., 0.1 to It has an imide content of at least 5% relative to the nitrogen content and theoretical maximum value comprised in the range of 9% by weight, preferably 0.5 to 7% by weight.

Based on IR analysis, these imide units are predicted to be cyclic even if such structures are not bound for the purposes of the present invention.

The process for the preparation of the imidized acrylic polymer according to the invention consists of the reaction of the modifier of formula (I) with an acrylic resin under ambient pressure, preferably under pressure below ambient pressure, and at temperatures above the melting point of the acrylic resin. .

Reaction pressures in the range of 760 to 10 ⁻² Torr, preferably 500 to 0.1 Torr, more preferably 760 Torr and in the range of 200 to 350 ° C., preferably 220 to 280 ° C. are most commonly used.

Modifiers are used in amounts ranging from 5 to 60 mole percent, preferably 10 to 50 mole percent, based on the acrylic monomer units.

According to a preferred form of the practical embodiment of the process of the invention the reaction between the modifier having formula (I) and the acrylic resin is carried out in the presence of a basic catalyst, an acidic catalyst and / or a transesterification catalyst.

These catalysts are high boiling point products which are stable under the reaction conditions; Preferably dicyclohexyl-amine, 1, 1, 3, 3, -tetramethyl-guanidine, 1,3-diphenyl-guanidine, quinoline, isoquinoline, 4-benzyl-pyridine, 4-phenyl-pyridine, 2 , 3-benzodiazine, 1,4-benzodiazine, 1-benzazine, 1,3-benzodiazine, N, N'-dicyclohexyl-carbodiimide, 2,2'-bipyridyl, Tertiary amines such as 2,3'-bipyridyl, 2,4'-bipyridyl or HCI, Sb ₂ O ₃ , Ti (OC ₄ H ₉ ) ₄ , NaNH ₂ , SnO ₂ , potassium alkoxide, alkoxy It may be selected from the group consisting of sodium sulfate, manganese acetate and the like.

The catalyst can be used in amounts as high as 30% by weight, even with respect to the total amount of the reaction mixture.

In addition, according to a more preferred form of a practical implementation of the process of the invention, the reaction between the modifier having formula (I) and the acrylic resin can be carried out in an extruder, mixer or similar device in which a gas recovery device is suitably installed. have.

The process of the present invention can be carried out using an acrylic resin dissolved in a molten state and a suitable solvent.

The imidized acrylic polymers of the present invention can be treated with techniques commonly used for the conversion of thermoplastic polymers, such as extrusion, injection molding, and the like, and can be used for the production of articles manufactured in any shape and / or dimension. have.

Moreover, such polymers can be used in the manufacture of sheets, films, tubes, filaments and the like.

The imidized acrylic polymers obtained after the process according to the invention can be mixed with suitable additives such as impact resistance products, pigments, fibers, inorganic fillers, flame retardants, stabilizers, lubricants, plasticizers and the like.

Foaming agents can be added to the polymers according to the invention, which polymers can be used in foamed form and are even more optionally mixed with fibers and / or inorganic fillers to produce manufactured products having low density and high mechanical properties.

The glass transition temperature (Tg) is determined using a differential caloric agent and is the temperature that corresponds to the point of refraction in the temperature plot when the heat capacity of the material changes. The temperature conversion rate is 20 ° C./min and the measurement is carried out by heating to 200 ° C. and then cooling.

The present invention has been set forth in the following examples in order to better understand and carry out, but not limiting the invention.

Example 1

A glass reactor equipped with a stirrer and an outlet for volatiles 25 g of a copolymer containing 98% by weight of methyl methacrylate and 2% by weight of methyl acrylate having a intrinsic viscosity of 0.34 dl / g in THF at 30 ° C. and benzamide 15 g are injected simultaneously under nitrogen atmosphere. The reaction mass is slowly heated to the melting point and then to 255 ° C. while distilling off the volatile reaction product.

The reaction was continued at 255 ° C. for approximately 3 hours and then the reactor was mechanically pumped for 15 minutes to maintain vacuum, the reaction mass was cooled to 150 ° C., refluxed with nitrogen, and the reaction product was brought to 50 ml of N, N. Dilution with '-dimethylformamide gives a solution in which the polymer is recovered by coagulation with methanol.

The product thus obtained is filtered off, washed with ether and dried in vacuo.

The polymer obtained had an intrinsic viscosity of 0.3 dl / g, a nitrogen content of 3.7% by weight and a glass transition temperature (Tg) of 155 ° C in THF.

Further, the thermogravimetric analysis (TGA) of the polymer sample at a temperature increase rate of 10 ° C./min under nitrogen atmosphere shows a weight loss of 0.45% within the temperature range of 50-300 ° C.

The IR spectra performed on the obtained product showed absorption bands at 1,698 cm ⁻¹ and 3240 cm ⁻¹ to confirm that the cyclic imide structure was formed as follows:

Example 2

The reaction is carried out in the same manner as in Example 1 by adding 0.2 ml of 4-benzyl-pyridine to the two reactants of Example 1.

The polymer thus obtained has an intrinsic viscosity of 0.28 dl / g, a nitrogen content of 2.9% by weight and a Tg = 160 ° C. in THF.

Example 3

The reaction is carried out in the same manner as in Example 1 except adding 8 ml of 4-benzyl-pyridine to both reactants and carrying out the reaction at 230 ° C.

The polymer thus obtained has an intrinsic viscosity of 0.28 dl / g in THF, a nitrogen content of 6.2% by weight and a Tg of 183 ° C.

Example 4

The reaction is carried out in the same manner as in Example 1 except for replacing benzamide with 18 g of aniseamide and performing it at 280 ° C.

The polymer thus obtained had an intrinsic viscosity of 0.29 dl / g, a nitrogen content of 2.33 wt% and Tg = 133 ° C.

Example 5

The reaction is carried out in the same manner as in Example 1 except for replacing benzamide with 7.3 g of acetamide and performing at 222 ° C.

The polymer thus obtained had an intrinsic viscosity of 0.34 dl / g, a nitrogen content of 0.84 wt% and Tg = 124 ° C.

Example 6

The reaction is carried out in the same manner as in Example 5 except that 1 ml of 4-benzylpyridine is added to the two reactants, and the reaction is carried out at 228 ° C.

The polymer thus obtained had an intrinsic viscosity of 0.28 dl / g, a nitrogen content of 2.39 wt% and Tg = 149 ° C.

Example 7

The reaction is carried out in the same manner as in Example 1 except for replacing benzamide with 16.2 g of acetamide and performing at 273 ° C.

The polymer thus obtained had an intrinsic viscosity of 0.31 dl / g, a nitrogen content of 0.52% by weight and a Tg = 131 ° C.

Example 8

The reaction is carried out in the same manner as in Example 1 with an acrylic resin having an intrinsic viscosity of 0.45 dl / g in chloroform at 23 ° C. and consisting of 90% by weight of methyl methacrylate and 10% by weight of ethyl acrylate.

The polymer thus obtained had a nitrogen content of 3% by weight and a Tg = 148 ° C.

Example 9

The reaction was carried out in the same manner as in Example 1 with an acrylic resin having an intrinsic viscosity of 0.7 dl / g in chloroform at 23 ° C. and composed of 65% by weight of methyl methacrylate and 35% by weight of styrene.

The polymer thus obtained has a nitrogen content of 2% by weight and Tg = 139 ° C.

Example 10

The reaction is carried out in the same manner as in Example 1, replacing benzamide with 15 g of N-phenyl formamide.

The Tg of the polymer thus obtained is 170 ° C.

Example 11

The reaction is carried out in the same manner as in Example 1 except that the methyl methacrylate / methyl acrylate copolymer has an intrinsic viscosity of 0.9 dl / g and replaces benzamide with 13 g of chloropropionamide.

The Tg of the polymer thus obtained is 175 ° C.

Claims (14)

Imide acrylic polymer obtained by the reaction of at least one modifier having the general formula (I) with an acrylic resin: R-X-NH-R '(I) Wherein R and R 'are the same as or different from each other, and are hydrogen, or an alkyl, cycloalkyl, aryl or alkylaryl group containing C ₁ to C ₂₀ , and X is -CO-, -CONH-,- It is a bifunctional group selected from the group consisting of NHCO-,-OCO-, -SO _2- , -C ₆ H ₄ SO _2- , and when R is different from R ', R may contain heteroatoms such as halogens. have. The modifier of claim 1, wherein the modifier having formula (I) is benzamide, aniseamide, acetamide, acetanilide, butyramide, benzanilide, propionamide, formamide, N-methyl-acetamide, N-methyl Imidization comprising benzamide, N-methyl-formamide, N-phenyl formamide, benzenesulfamide, ethyl carbamate, benzhydrazide, chloropropionamide, N, N'-dimethylurea Acrylic polymer. The intrinsic viscosity according to claim 1 or 2, at 30 ° C., intrinsic viscosity in tetrahydrofuran (THF) in the range of 0.01 to 7 dl / g, nitrogen content in the range of 0.1 to 9% by weight and Imidized acrylic polymer having an imide unit content of at least 5% relative to the theoretical maximum. The imidized acrylic polymer according to claim 3, wherein the imide unit is in cyclic form. A process for preparing the imidized acrylic polymer of claim 1 consisting of the reaction of a acrylic resin with a modifier of formula (I) at ambient pressure or at a pressure lower than the ambient pressure and at a temperature above the melting point of the acrylic resin. 6. The process according to claim 5, wherein the reaction is carried out at a pressure comprised in the range of 760 to 10 ^-2 Torr and at a temperature comprised in the range of 200 to 350 ° C. 7. Process according to claim 5 or 6, wherein the modifier is used in an amount comprised in the range of 5 to 60 mole percent relative to the acrylic monomer units. A process according to claim 5, wherein the reaction between the acrylic resin and the modifier of formula (I) is carried out in the presence of a basic catalyst, an acidic catalyst and / or a transesterification catalyst. 9. The catalyst of claim 8 wherein the catalyst is dicyclohexyl-amine, 1, 1, 3, 3-tetramethyl-guanidine, 1, 3-diphenyl-guanidine, quinoline, isoquinoline, 4-benzyl-pyridine, 4-phenyl -Pyridine, 2, 3-benzodiazine, 1, 4-benzodiazine, 1-benzazine, 1, 3-benzodiazine, N, N'-dicyclohexyl-carbodiimide, 2, 2'- Tertiary amines such as bipyridine, 2, 3'-bipyridyl, 2, 4'-bipyridyl or HCI, Sb ₂ O ₃ , Ti (OC ₄ H ₉ ) ₄ , NaNH ₂ , SnO ₂ , alkoxylation Potassium, sodium alkoxide, manganese acetate, and the like. The method according to claim 5, wherein the acrylic resin is used in a molten state and dissolved in a solvent. 6. A process according to claim 5, wherein the reaction between the modifier having formula (I) and the acrylic resin is carried out in an extruder, mixer or similar device equipped with gas removal means. The process of claim 6 wherein the reaction is carried out at a pressure comprised in the range of 500 to 0.1 Torr and at a temperature comprised in the range of 220 to 280 ° C. 8. Process according to claim 7, wherein the modifier is used in an amount comprised in the range of 10 to 50 mole% relative to the acrylic monomer units. 6. The process according to claim 5, wherein the reaction is carried out under a pressure of 760 Torr.